Httmett p



. --.--u 1rE.D vsrAT-Es "P OFFICE" I Patented Dec. 1928.

' r. canmmr 'SCHENECTADY. NEW roux, ASSIGNOB 950 GENERAL ELECTRIC I Y ,commmr, A conrona'non ormaw xonx.

\HIGB-FREQUENCY SIGNALING; srsrmr, v

-My invention relates to high frequency signalingsyste'rns, and. particularly to signaling systems adapted for single frequency du lexoperation.

n'systems of this type the output of the transmitting circuit and the input of the receiving circuit are usually'inductively associated so that during periods of transi nis-r sion energy is sup )licd from the output of theitransmittin'g circuit to "the input of the receiving circuit, where it produces undesirable. efi'ects. Heretofore' means have been provided for protecting the receving circuit flfroqr these undesirable effects, such means 752243, filcdNovember' 10 24,- nuueq ,High frequency duplex signalling system" accomplisl1ed by controlling the discharge in energizing the filaments of these devices.

The purpose ofmy invention is to overcome these and other disadvantages of the prior circuitsand to provide a. protective device for the receivingcircuitwhich is more simple in its circuit construction than those heretofore proposed, and which operates sub-' stantially"simultaneously with the function.

ing of the transmitting circuit.

In in'vv copending application; Serial No.

I have shown an electron discharge device connected in shunt with the receivingcircuit to protect it from-energy received, from the associated transmitter. In accordunce with my pres'entin'venhon the desired result 15 7 device or discharge devices, each of which comprisesa normally inactive shunt to.the

receiving circuit in response to operation of.

the transmitter. 'r

The novel features which I believe to be characteristic of invention are set forth with particularity in the appended claims;

Application Med January 14, 1927. Serial No. 161,189.

My invention itself, however, both to organization and method of operation will best be understood by reference to the follow- 5 ing description taken inconnection with the v accompanying drawing, in which I have illustrated diagrammatically one form of my'in vention. y

Referring to the drawings, 1- denotes'a cir- I cult leading to'anantenna or .to wire lines depending upon the-particular application for which the systeni' is employed, 2 indicates generally the ,1QCQlVlllg;ClICl1lt, 3 indicatesgcnerally the transmitting circuit and 4 'in- 05 dicates the usual coupling transformer for connecting the input circuit ofthe-receiver and the output; circuit .of the transmitterwith the common: antenna-or 'wire line 1. 5 indicates the usual telephone. circuit or voice channel-leading to the-operht-ors station and 6 indicates a'coupling transformer for connecting the output'circuit'of the receiver and the input circuit of the transmitter with the voicechannel 5. '7 indicatesthe usual net work circuit for balancing the three ivinding tr'a'nsfomierfi. since myinvention is pri- 1 marily concernedwiththe receiving circuit,

only so much of the tr'ans nitting circuit as is necessary to an understanding of my inven: 30

tion is shown in the drawing. Hence the apparatus which is associated with the audio J I frequency channel of .the'transmitting an; cuithasbeen designatediby the rectangle ated with the .rad1o frequency;. channel has been designated by the rectangle :10, 11 in 'dicates anelectron discharge device which may be utilized as tgg'gfierator. of the radio;

and likewisefthe apparatus which We 1 f frequency-. i'olta T loyeidigging tmns- -missionandl2iii tficatesasecondelehtron dis-" charge-dev'icein'the tmnsmitting circuit for I controlling the o'peration oftheelectron;dis- I lll'iflie rece ving c1rcuit',' ,13 indicates, an [95.

elcctmndischarge deviceivhihlma 4 .ployed as a detector. .lt'indicatesthenput"" 'jj j' circuit to this detector whichis suppliediwithe f energy through transforiner 15,' link.circuit 16 ;-and coupling transformer-'4 iztrnm' thc:1qo

antenna or wirezline l. {,Forthe {pu-r j oi; tuning these circuits the'vanable condenser I 1.7' has been provided in series with thqylfilflk circuit 16 and the variable c0n 1enser =1iinp shunt Jwith theinput circuit 14. '19 and indicate electron discharge devices which-are connected in shunt relation with the input circuit 14 and the linkcircuit 16, res ectively.- The cathode'21 of the electron disc. argede vice 19 is connected through cathode conductors 30 to one side of the input circuit 14 at the point 22, and the anode23 of the electron discharge device 19 is connected through a suitable source of potential 24 to the oppo site side of the. input circuit 14, Likewise the cathode 25 of the electron discharge device 20 is connected to one side of the link circuit 16 at the point 26 and the anode 27 is connected through a suitable source of poten "tial 28 to the opposite side of the link circuit 16. ,The cathodes 21 and 25, together with the cathode 29 of the detector 13, have been connected .in parallel by the. conductors 30 across a suitable source of potential 31, this arrangement being adopted as a matter of convenience and economy since any suitable means may be employed for energizing the cathode. The grid 32 of the electron discharge device 20 and the grid 330i the-electron discharge device 19 are connected together througlrconductors 34 and 35 and they are also connected through a suitable source of potential 36, resistance 37 and conductor 38 .to the cathodecond uctors 30.- One side of the resistance 37 is connected through conductor 38 to the negative side of a high voltage source 39'. and to appropriate conductors in the audio channels of the transmittingapparatus 9. .The opposite side of resistance 37 is connected through a conducvtor' 4() to the cathode 41 of the electron discharge device 12 in the transmitting circuit.

A bypass condenser 42 isconnected across the resistance 37 for the purpose of shuntingalternating currents which may fiow 1n the.

conductor 40 and conductor 38 out ofthe resistance 37-. The cathode 41* of the a electron discharge device 12 and the cathode .of'the electron discharge device 11 antitanintermediate point 50 connected to the cath- 43 of the electron discharge device 11 are energized from a suitable source of energy 44 through cathode transfor1ners 45 and cathode conductors 57 and 56 respectively.

46 represents the usual oscillatory circuit of the alternating current generator 11, having one extremity 47 connected to the anode'48 of the electron discharge device 11,.and itsopposite extremity 49 connected to the grid ode 43 and through the conductor 51 to the .anode 52 of the electron discharge device 12. The anode 48 is provided witha suitable high potential from the high potential source 39 through the choke coil 53- I The operation of my device isas follows. During normal operation of the system, when thetransmittin circuit is idle and reception is taking place throughthe receiving channel f2, th'e.electron dischargedevices 19 and 20 he, inactive. I ."negative potential is impressed upon the.

"This is because a high control elements '33 and 32 of these devices .38, resistance 3?, source of potential 36 and conductors 35 and 34. Hence no current will flow through the anode cathode circuit of these devices and they will have no effect 7 uponthe system. Reception will, therefore, take place in the usual'way. i v

Assume now that theoperator speaks into the microphone at the operators station. Voice frequencies will then be transmitted 8 through the voice channel 5 coupling transformer 6 and audio apparatus 9, from which they will'be-impiess'ed upon'the grid 55of the, control electron discharge device 12, causing this grid to assume a positive potential with frespect to the cathode 41. This, in turn, de-

creases the resistance betw'eenthe cathode 41 and anode 52 and thereby causes-a direct currentpotential-to appear between tlie'cathode 43 and anode 48 of oscillation generator 11. This being true radio frequency currents will be generated by the-generator 11 and inipressed upon the amplifying apparatus 10 in theusual way. Under this condition. a directcurrent will flow from the source 39 05 through a circuit includingthe choke coil 53, "anode 48, space between the. anode 48 and the cathode 43 of the electron discharge device 11, cathode 43, cathode conductors 56, con-' ductor 51, anode 52 space between the anode 10 52 and cathode 41 oelectron discharge device a potential will build up on resistance 37 6 which will have the ptalrity indicated in thedrawing. This poten al being in series re-- la'tion with that of the source 36 in the grid circuits of the electron'discharge devices .19 and 20 will overcome the' otential of'the 1. source 36 and cause the'gri s 33 and 32to be impressed with a positive potential with re spect to theirrespective cathodes Current will-then flow from one's ide of the link cir- I cuit 16 through the electron discharge device 20 to the opposite'side of this circuit and likewise, current will flow. fronf one sideof the input circuit. 14, thrquglgthe electron dis- 1 charge device 19 to the opposite side and these devices will constitute comparatively low re- 1 sist-ance shunts across their respective tuned -c1rcu1ts. This'bemg'the ease,'these circuits will be detuned and the trafismission efficiency of the system-will be' diminished. Hence energy which maybe. fed-from the outpgt circu1t 58 of. the transmitting CLCllit 3 t ;d uced to sucha degree as to produce no undesirable effects upon the receiving apparatus.

When theope-ratorstops speaking into the microphone'at the operators station thepo- -tdtential on-iresistance 3'Zwill diminish and that of the source 36 will again become effifectiveu on the grids '33 and' -32 of the electron .discii Y causin'gthein to assume ancgative' potential.

Hence these electron discharge devices again Ibecomeinoperative and reception will again tal e place 1n*the normalmanner.

While in the particular embodimcntof my invention shown in the drawing I have shown 3 two electron discharge devices, it is to be ted, in which case the other would serve to :Fciate'd and, acting through the transformer 15 "w0uld detune the other tuned circuits of the system: Likewise, it may .be' preferred to use fonly the one tuned circuit, in which case the thecoupling. transfonner4.

--"Thus it'will-belappa'rent that I-havepro- ,vided adevice -'which, among other advantion' than those heretofore. proposed, which 0 rates-substantially simultaneously with {thereby substantially eliminating any undei six-able eflectsresulting .tromtime delay tie-- tween 'the .initiation'of high frequency cur- "rents in the transmitting circuit and.the ap asiplication ofthe protective'deviw to the re- .c'eivingcireuit and which absorbs only. a hnegligible amount of energy fromthe transmittin circuit. v

Winle I have illustrated and described only {one embodiment of my invention, it will be limited to I the particular embodiment indicated, but that many modifications'in the circu'it arrangmentsand instrumentahtiesem- 'madewithout departing from the scope theretioning'of said transmittingcircuit, said control element being associated with said source f-of potential; s

'2. Ina signaling system employ ng both-a accesses arge devices 19 and 20 respectively,

"' u nderstood that either of these may be omit-.

- detune the circuit with which it is input circuit 14'jwould beco'upled directly to.

sponsive to the functioning of said transmit tages', is more simple in its circuit construe-- 0 t e -.functioning of the transmittingcircuit' {obvious that my invention is by'no-means' ployed in'carryingout my invention may be nfas forth in the appended claims. r

- @f'iwhicli is'variabie responsively to the funcj 'transinitting circuit and a receiving circuit,

means for. protectim said receivingcircuit .from said transmitting circuit, said means comprising an electron discharge dcvicc'hav- 1/ ing an anode, a, cathode and a control Jel'e; ment, said anode being associated with side .of said receiving circu'it,'s'aid cathodd being associated with the other side of said receiving circuitand a source enema c1ir rent potential .which is variable responsively to the 'fun'ctionin r of said transmittingci'rc'uitfsaid-contro element being associated with'sa'id source of Potential." l 3. Inc. signaling system employing a trans mitting circuit and a receiving circuit, meahs for protecting said receiving circuit from said transmitting circuit comprising a num- 'ber of tuned'circuits in said receiving circuit,

an electron dischargegdevice associated with each; of said tuned' circuits and having an anode, a cathode and a control element each -of said anodes bein connected to one side of one of said tuned circuits, each (sf-said cathodes being connectedto the other-sideofithe corresponding tunedcircuits and means re-- ting circuit for'controlling'the potential of said control elements. A 1 4. 'In a signaling system employing atra'ns- :mitting' circuit and ;a receiving circuit, lmeans for protecting said receiving circuit from said transmitting circuittompris'ing a number of tuned circuits in said zreceivingcircuit,- an electron dischargedevice aiss'o-;

ciated with each of said tuned circuits and having an anode, a cathode anda control element, each of said anodes being. connected to one side of one of said tuned circuits, each of said cathodes being connected the'other side of the corresponding tuned circuitsand means comprising a'source of direct current potential which is variable responsively to the functioning of said transmitting circuit for controlling the potential of said control elements.

5. In a signaling syswm employingatransmitting circuit and a receiving circuit, mezzo:

for protecting said receiving circuit: in

said transmitting circuit com'prising-a-number of tuned ircuits in said recciving circuit,. an electron discharge device associated with:

each of saidtunedcircuits and'havingfanl;

anode, acathode and, a grid, each of said, anodes being connected to oneside of one of- 1 said tuned circuits and each of said cathigles being connected to the'ot-hei' side of the corv responding tuned circuits and means responsire to the functioning of said transmitting circuit for varying the potential on sa d grids, said means comprising a resistance cpn- .nected between 'said cathodes andsaid gr1ds,. .125 the current in said resistance being variablq;

responsively to the functioning of said transmitting circuit.

6. .In a signaling system, employinga= transmitting circuit and a receiving crrcuit.

said receiving circuit incl riding a 'iittiitliciof each of said tuned circuit-s and having an anode, ii cathode and-a grid',,eac, h of said anodes being connected to one side of one of said'tu ed circuits and each of said cathodes being connected to thc other side of the'corresponding tuned circ iits,"an oscillation gencrater in said transniittingcircuit having an current. flowing in said anode circuit fOl'fCOib. trolling t-hc potential on said grids.

" 7. In a signaling system employing-a transmittingcircuit and ;a receiving circuit, said fi ing circuit including a number of tuned ts, a protective devicecomprising an electron discharge device associated u'itlr,

each of said tuned circuits having an anode,

.a cathodeand. a grid, each of said anodes being connected to one side of one of said tunedcircuits and each of said eathodcshcing connected to the other side oftlie corresponding tuned circuits, an oscillationgenorator iii-said transmitting circuit having an anode circuit, and a resistance-.connected in, said anode circuit, said rcsistancebeing alsoconnected between the grids and cathodcs of said electron discharge devices.

8. In a signaling system ei' iploying a transinittingcircuitand a receiving circuit,

said receiving circuit including a; plurality of associated tuned circuits, a, protective device comprising an'electron discharge device having an anode, a cathode vand a grid, said anode being connected to one side of one of said tuned circuits andjsaidcathod'e being connected to the other side-of said-t-uned c-ircuit-,'-an oscillation generato'r-i nrsaid transmitting circuit having an anodeicirc-uiti' and means responsive to the current flowing in said anodccii cuit for varying, the potential on said grid.

" -9. In a signaling system employing a transmitting circuit and a receiving circuit, said;

receiving circuit including. a plurality of as sociated'tuned circuits, a protective device comprising-an electron dischargedevice havingan anode, acathode anda grid, said. anode being connected to=one side-oi one of said tuned circuits and said=cathodc living connected to the other side of Silltlitllittl circuit, an oscillation generator-in said transiiiitting circuit having-an anode circuitand means responsive to tlie current. flowing in said anode circuit .t'onvarying tlic potential on said grid, said means comprising a resist-, ance connected in saidf-ano'decircuit and hetii'e'en the cathode and grid of said clcc- 'tron discharge device.

10. Ina signiiling -systeiii. employing a transmitting circuitand areceiving circuit, means for protecting said receiving circuit from said transmitting circuit. comprising an electron discharge device having a cathode and ananode, said cathode being connected" to one side of said receiving circuit, and said anode being associated with the other side of said receiv ng circuit, a vacuum 'tubeoscillatio generator n sa d transmitting cir-.

c'uit liavingananode circuit, and means in said anode circuit for'controlling the inipedance' between said first mentioned vcathode I and anode 11.1n asignaling: system employing a anode circuit and means responsive to the number of tuned circuits-in said'receiving circuit, an electron discharge device connected in shunt relation with oneof'said.

tuned circuits, a vacuum tube oscillation generator-in sai'd transmitting circuithaving an anode circu t and means 1n said. anode circuit for controlling the 'ini 13. In a'higli frequency signaling system employing a transmitting circuit and a receiving en -cu1t,.means.for protecting said danceof said shuntv connected electron discharge device.

receiving .-circuit--,from. interference from said transmitting'cireuit comprising a number of tuned circuits in said receiving circuit, an electrondischarge device having a cath ode. an anode and acontrol element associ-- ated with each ofsaid tuned circuits, said anodes heing'associated with one side of said tuned circuits and said cathodes being asso- (.'Iilt0(l with the opposite sides of the corretron discharge oscillatiorr generator having an anode circuit-,- a receiving circuit. a 'liOl malty inactive shunt for said receiving circuit and means responsive to current flowing in said anode circuit for controlling said normally inactive shunt.

15. The combination in a high frequency signaling system, a transmittin circuit incl uding an electron discharge oscillation gen-- erator having an anode circuit, 'a'. receiving.

circuit including a signal apparatus,'a"tuned circuit'for controlling. the supply of high frequency currents to said signal apparatus moegses 5 and means responsive to the mil-rent flowing for controlling a characteristie of said r e in said anode circuit for controlling said ceiving circuit, and means responsive b ocubtunedcircuit. I rent flowing in said anode'cncuit for 'on- 1G 4 16. The combination ina signaling system trolling said first means;

{i of a, transmitting circuit including an elec- In witness whereof, I have hereunto s ifin tron discharge oscillation generator having my hand this 13th.dav of January 1927. an anode circuit, a receiving cllqlit, means EMMETT F. (minim 

